TWI533007B - Circuits and methods for measuring a cell voltage in a battery - Google Patents

Description

Battery measuring circuit, system and method

The present invention relates to the field of batteries, and more particularly to a battery measuring circuit, system and method.

1 is a schematic diagram of a battery measurement circuit 100 that conventionally measures the cell voltage of a battery cell within a battery pack. The battery measuring circuit 100 includes a battery pack 110, a potential transfer circuit 120, a resistor group 130, a capacitor bank 180, a measuring unit 140, a current generator 160, and a switch group 170. As shown in FIG. 1, the battery pack 110 includes battery cells 111 to battery cells 113 coupled in series. The resistor group 130 includes a resistor 131 to a resistor 134. The capacitor bank 180 includes a capacitor 182, a capacitor 184, and a capacitor 186. The resistor bank 130 and the capacitor bank 180 filter noise on signals transmitted between the battery pack 110 and the switch bank 170. The switch group 170 selects a battery unit from the battery unit 111 to the battery unit 113. The potential transfer circuit 120 provides a transfer voltage proportional to the cell voltage of the selected battery cell. The measuring unit 140 calculates the cell voltage of the selected battery cell based on the transfer voltage generated by the potential transfer circuit 120.

The potential transfer circuit 120 consumes the current of the battery pack 110. For example, when the battery unit 111 is selected, the potential transfer circuit 120 consumes the current _I'cons1 and the current _I'con2 . The current _I'con1 flows out from the positive terminal of the battery unit 111, flows through the resistor 131 and the switch group 170, and flows to the potential transfer circuit 120. The current I' _{cons2 flows} from the negative terminal of the battery unit 111, flows through the resistor 132 and the switch group 170, and flows to the potential transfer circuit 120. The voltage drop across resistor 131 and resistor 132 can have a negative impact on the accuracy of the cell voltage measurement. To mitigate the negative effects, current generator 160 produces a compensation current _I'comp2 . The compensation current I' _comp2 flows through the potential transfer circuit 120, the switch group 170, and the resistor 132, and flows to the negative terminal of the battery unit 111. Thus, as compensation current I _'comp2 current _I' cons2 substantially equal, the voltage drop can be ignored on the resistor 132.

However, the positive terminal voltage of the battery unit 111 and the power supply of the current generator 160 The difference between the pressures may be too small, so that the current generator 160 cannot generate a compensation current flowing into the positive terminal of the battery unit 111 to compensate for the voltage drop across the resistor 131. Thus, the voltage drop across resistor 131 still has a negative impact on the accuracy of the cell voltage measurement.

It is an object of the present invention to provide a battery measuring circuit comprising a measuring circuit and a current generator. The measuring circuit includes a first port and a second port, respectively coupled to a positive terminal and a negative terminal of a battery unit through a first resistor and a second resistor, wherein the measuring circuit consumes a first current and a second current flowing from the positive terminal, flowing through the first resistor, flowing to the first port, the second current flowing from the negative terminal, flowing through the second resistor, flowing to the second port . The current generator is coupled to the battery unit, and generates a first compensation current according to the first current. The first compensation current flows from the positive terminal, flows through the first resistor, and flows to the first port, where the first When the compensation current is disabled, the measuring circuit receives a first voltage difference between the first port and the second port; when the first compensation current is enabled, the measuring circuit receives the first port and the second port a second voltage difference between the two; the measuring circuit calculates a cell voltage of the battery cell based on the first voltage difference and the second voltage difference.

The present invention also provides a battery measuring system, comprising: a plurality of battery cells; a plurality of resistors coupled to the plurality of battery cells; a measuring circuit comprising: a first port, through a first one of the plurality of resistors a positive end of the first battery unit is coupled to the first battery unit; and a second port is coupled to a negative end of the first battery unit through a second one of the plurality of resistors, wherein The measuring circuit consumes a first current and a second current, the first current flows from the positive terminal, flows through the first resistor, and flows to the first port, and the second current flows out from the negative terminal, and flows through the a second resistor, flowing to the second port; and a current generator coupled to the plurality of battery cells, generating a first compensation current according to the first current, the first compensation current flowing from the positive terminal, flowing through the a first resistor flowing to the first port; wherein, when the first compensation current is disabled, a first voltage drop is generated on the first resistor, and when the first compensation current is enabled, the first resistor generates a first Two voltage drops, the measurement circuit root The first voltage drop and said second voltage drop of the cell voltage calculating a first battery cell.

A battery measuring method includes: consuming a first current and a second a current flowing from a positive end of a battery unit, flowing through a first resistor to a first port, the second current flowing from a negative end of the battery unit, flowing through a second a resistor, flowing to a second port; generating a first compensation current according to the first current, the first compensation current flowing from the positive terminal, flowing through the first resistor, flowing to the first port; the first compensation current is divided Receiving a first voltage difference between the first port and the second port; and receiving a second voltage difference between the first port and the second port when the first compensation current is enabled; The first voltage difference and the second voltage difference calculate a cell voltage.

100‧‧‧Battery measurement circuit

101~104‧‧‧Double junction transistor

110‧‧‧Battery Pack

111~113‧‧‧ battery unit

120‧‧‧potential transfer circuit

130‧‧‧Resistance group

131~134‧‧‧resistance

140‧‧‧Measurement unit

160‧‧‧current generator

170‧‧‧ switch group

180‧‧‧capacitor group

182, 184, 186‧‧‧ capacitors

200‧‧‧Battery measurement circuit

210‧‧‧Battery Pack

211~213‧‧‧ battery unit

220‧‧‧potentiometric transfer circuit

230‧‧‧resistance group

231~234‧‧‧resistance

240‧‧‧Measurement unit

260‧‧‧current generator

270‧‧‧ switch group

271~276‧‧‧ switch

280‧‧‧capacitor group

282, 284, 286‧‧ ‧ capacitor

300‧‧‧Battery measurement circuit

331~334‧‧‧resistance

341, 342‧ ‧ amplifier

352‧‧‧ Analog/Digital Converter

362‧‧‧Control circuit

382, 384‧‧‧ current source

392‧‧‧Switch

400‧‧‧Battery measurement circuit

422‧‧‧ switch

500‧‧‧ equivalent circuit

600‧‧‧ equivalent circuit

700‧‧‧Battery Measurement Circuit

761~763, 765, 767, 768‧‧‧ metal oxide semiconductor field effect transistor

764‧‧Amplifier

766‧‧‧resistance

801~804‧‧‧Metal Oxide Semiconductor Field Effect Transistor

900‧‧‧Battery measurement method flow chart

902, 904, 906, 908, 910‧ ‧ steps

1000‧‧‧Battery measurement circuit

1040‧‧‧Measurement unit

1060‧‧‧ Current generator

The technical method of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments to make the features and advantages of the present invention more obvious. 1 is a schematic diagram of a conventional battery measuring circuit 200 for measuring the cell voltage of a battery cell in a battery pack; FIG. 2 is a battery measuring device for measuring a cell voltage of a battery cell in a battery pack according to an embodiment of the present invention. FIG. 3 is a schematic structural diagram of a battery measuring circuit for measuring a cell voltage of a battery cell in a battery pack according to an embodiment of the present invention; FIG. 4 is a view showing a battery according to another embodiment of the present invention. A schematic diagram of a battery measuring circuit of a cell voltage of a battery cell in a group; FIG. 5 is a schematic diagram of an equivalent circuit of the circuit of FIG. 4; FIG. 6 is a schematic diagram of another equivalent circuit of the circuit of FIG. 7 is a schematic structural view of a battery measuring circuit for measuring a cell voltage of a battery cell in a battery pack according to still another embodiment of the present invention; FIG. 8 is a circuit diagram of the amplifier of FIG. 7; A flow chart of a battery measuring method for measuring a cell voltage of a battery cell in a battery pack according to an embodiment; FIG. 10 shows another method according to the present invention. Embodiment circuit block configuration of the battery cell voltage measuring embodiment of a measurement cell battery. FIG.

A detailed description of the embodiments of the present invention will be given below. While the invention will be described in conjunction with the embodiments, it is understood that the invention is not limited to the embodiments. Rather, the invention is to cover various modifications, equivalents, and equivalents of the invention as defined by the scope of the appended claims.

In addition, in the following detailed description of the embodiments of the invention However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail in order to facilitate the invention.

2 is a block diagram showing the structure of a battery measuring circuit 200 for measuring a cell voltage of a battery cell in a battery pack according to an embodiment of the present invention. The battery measuring circuit 200 includes a battery pack 210, a resistor group 230, a capacitor bank 280, a switch group 270, a current generator 260, and a measuring circuit. The measuring circuit includes a potential transfer circuit 220 and a measuring unit 240. The battery pack 210 includes battery cells 211 to 213 that are coupled in series. The battery pack 210 can also include other numbers of battery cells, and the invention is not limited thereto. The resistor group 230 includes a resistor 231~ a resistor 234. Capacitor bank 280 includes capacitor 282, capacitor 284, and capacitor 286. Resistor group 230 and capacitor bank 280 filter noise on signals transmitted between battery pack 210 and switch block 270.

The switch group 270 includes switches 271 to 276, and the battery cells to be measured by the measurement circuit 200 are selected from the battery cells 211 to 213. By selecting a battery cell, switch bank 270 provides a voltage difference between first port T1 and second port T2 indicating the cell voltage of the selected battery cell. For example, when the switch 271 is turned on with the switch 273 and the other switches in the switch group 270 are turned off, the battery unit 211 is selected, and the voltage difference provided between the first port T1 and the second port T2 of the switch block 270 indicates that the switch is selected. The cell voltage of the battery unit 211.

The potential transfer circuit 220 receives the voltage difference between the first port T1 and the second port T2, and supplies the measurement unit 240 with a transfer voltage difference proportional to the voltage difference between the first port T1 and the second port T2. The potential transfer circuit 220 consumes current from the positive and negative terminals of the selected battery cell. For example, when the battery unit 211 is selected, the first port T1 is coupled to the positive terminal V _{+ of the} battery unit 211 through the resistor 231 and the switch 271, and the second port T2 is transmitted through the resistor 232 and the switch 273 and the negative terminal V of the battery unit 211. _- Coupling. In an embodiment of the invention, resistor 231 is also referred to as a first resistor and resistor 232 is also referred to as a second resistor. The potential transfer circuit 220 consumes the first current I _cons1 and the second current I _cons2 . The first current I _{cons1 flows} out from the positive terminal V _{+ of the} battery unit 211 , flows through the resistor 231 and the switch 271 , and flows to the first port T1 . The second current Icons2 flows from the negative terminal V _{− of the} battery unit 211 , flows through the resistor 232 and the switch 273 , and flows to the second port T2 .

The current generator 260 generates a first compensation current I _comp1 and a second compensation current I _comp2 according to the first current I _cons1 and the second current I _{cons2 , respectively} . The first compensation current I _comp1 flows out from the positive terminal V _{+ of the} battery unit 211 , flows through the resistor 231 and the switch 271 , and flows to the first port T1 . The second compensation current I _{comp2 flows} from the second port T2, flows through the switch 273 and the resistor 232, and flows to the negative terminal V _{- of the} battery unit 211. In one embodiment, the first compensation current I _comp1 and the second compensation current I _comp2 are proportional to the first current I _cons1 and the second current I _{cons2 , respectively} .

The current generator 260 can enable or disable the first compensation current I _comp1 according to the control signal CTRL from the measurement unit 240. When the first compensation current I _{comp1 is disabled} , the potential transfer circuit 220 receives the first voltage difference between the first port T1 and the second port T2. When the first compensation current I _{comp1 is} enabled, the potential transfer circuit 220 receives the second voltage difference between the first port T1 and the second port T2. Correspondingly, when the first compensation current I _{comp1 is disabled} , the potential transfer circuit 220 provides a first transfer voltage difference V _O1 for indicating the first voltage difference. When the first compensation current I _{comp1 is} enabled, the potential transfer circuit 220 provides And a second transfer voltage difference V _O2 indicating the second voltage difference.

When the first compensation current I _{comp1 is disabled} , the measuring unit 240 measures the first transfer voltage difference V _O1 from the potential transfer circuit 220. When the first compensation current I _{comp1 is} enabled, the measuring unit 240 measures the second from the potential transfer circuit 220. Transfer voltage difference V _O2 . The measuring unit 240 calculates the cell voltage of the selected battery cell 211 based on the first transfer voltage difference V _O1 and the second transfer voltage difference V _O2 . More specifically, in one embodiment, the measuring unit 240 calculates a third voltage V _O3 proportional to the first transfer voltage difference V _O1 and subtracts the second transfer voltage difference V _O2 from the third voltage V _O3 , Further, the cell voltage of the selected battery cell 211 is calculated.

In operation, when the battery cell 211 is selected, and the control signal CTRL has a first voltage value (e.g., logic low level), the current generator 260 in addition to the first compensation current I _comp1 and enable a second compensation current I _comp2 . A first voltage drop V _DROP1 is produced across resistor 231. It is substantially equal to a second current _I cons2 In one embodiment, the second compensation current I _comp2 the potential of the transfer circuit 220 is consumed. Therefore, the second compensation current I _comp2 and the second current I _cons2 cancel each other out, and the voltage drop across the resistor 232 is negligible. The potential transfer circuit 220 receives the first voltage difference V _DIFF1 between the first port T1 and the second port T2. The relationship between the cell voltage V _{CELL of the} battery unit 211 and the first voltage difference V _DIFF1 is: V _DIFF1 =V _CELL -V _DROP1 (1)

When the battery cell 211 is selected, and the control signal CTRL with a second voltage value (e.g., logic high level), the current generator 260 simultaneously enabling the first compensation and the second compensation current I _comp1 current I _comp2. A second voltage drop V _DROP2 is generated across resistor 231. In one embodiment, the first compensation current I _COMP1 the potential of the transfer circuit 220 is proportional to the current I consumed by _cons1. Therefore, the relationship between the first voltage drop V _DROP1 and the second voltage drop V _DROP2 is: V _DROP2 = L × V _DROP1 (2) where L is a constant indicating the first voltage drop V _DROP1 and the second voltage drop V proportional coefficient between _DROP2, and L is equal to _{(I cons1 + I comp1) /} I cons1. The potential transfer circuit 220 receives the second voltage difference V _DIFF2 between the first port T1 and the second port T2. Assuming that the voltage drop across the resistor 232 can be ignored, the relationship between the cell voltage V _CELL and the second voltage difference V _DIFF2 is: V _DIFF2 = V _CELL - V _DROP2 = V _{CELL -} L × V _DROP1 (3)

The potential transfer circuit 220 receives the first voltage difference V _DIFF1 and the second voltage difference V _DIFF2 , respectively, and outputs a first transfer voltage difference V _O1 and a second transfer voltage difference V _{O2 , respectively} . The measuring unit 240 measures the first voltage difference V _DIFF1 and the second voltage difference V _{DIFF2 by} measuring the first transfer voltage difference V _O1 and the second transfer voltage difference V _O2 , and according to the first transfer voltage difference V _O1 and the second transfer voltage difference V _O2 calculates the cell voltage V _CELL . In one embodiment, the relationship between the first transfer voltage difference V _O1 and the first voltage difference V _DIFF1 and the relationship between the second transfer voltage difference V _O2 and the second voltage difference V _DIFF2 are: V _O1 =K×V _DIFF1 = K × (V _CELL - V _DROP1 ) (4)

V _O2 = K × V _DIFF2 = K × (V _{CELL -} L × V _DROP1 ) (5) wherein K is a constant indicating a proportional coefficient between the first transfer voltage difference V _O1 and the first voltage difference V _DIFF1 , A scaling factor between the second transfer voltage difference V _O2 and the second voltage difference V _DIFF2 is indicated. The measuring unit 240 calculates a third voltage V _O3 proportional to the first transfer voltage difference V _O1 , and V _O3 is: V _O3 = L × V _O1 = L × K × V _{CELL -} L × K × V _DROP1 (6) The second transfer voltage difference V _O2 is subtracted from the third voltage V _O3 , and the measuring unit 240 can calculate the cell voltage V _CELL , V _CELL is: V _CELL = (V _O3 - V _O2 ) / (L × KK) (7)

Correspondingly, when the first compensation current I _{comp1 is disabled} , the measurement circuit receives the first voltage difference V _DIFF1 between the first port T1 and the second port T2; when the first compensation current I _{comp1 is} enabled, the measurement circuit receives the first port A second voltage difference V _DIFF2 between T1 and the second port T2. The measuring circuit calculates the cell voltage V _{CELL according} to a proportional coefficient L between the first voltage difference V _DIFF1 , the second voltage difference V _{DIFF2 ,} and the second voltage drop V _DROP2 and the first voltage drop V _DROP1 .

The advantage is that the first compensation current I _comp1 flowing from the positive terminal V _{+ of the} battery unit 211 through the resistor 231 is generated, and the first port T1 and the first port are respectively measured when the first compensation current I _{comp1 is disabled} and enabled. The voltage difference between the two ports T2 can reduce or eliminate the negative impact of the first voltage drop V _DROP1 on the resistor 231 on the measurement of the cell voltage.

The battery measuring circuit 200 can measure the cell voltage of the battery unit 212 and the battery unit 213 in the same manner, and details are not described herein again. Further, when the cell voltages of the battery unit 212 and the battery unit 213 are measured, the direction of the compensation current may be different from the above method. For example, when the battery unit 213 is selected, the potential transfer circuit 220 consumes the third current I _cons3 and the fourth current I _cons4 . The third current I _{cons3 flows} from the positive terminal V' _{+ of the} battery unit 213, flows through the resistor 233 and the switch 274, and flows to the first port T1. _I cons4 fourth current from the negative terminal of the battery cell of V 213 _'- effluent flowing through the resistor 234 and a switch 276, to the second port T2. The current generator 260 generates a third compensation current I _comp3 and a fourth compensation current I _comp4 according to the third current I _cons3 and the fourth current I _{cons4 , respectively} . The third compensation current I _comp3 flows out from the first port T1, flows through the switch 274 and the resistor 233, and flows to the positive terminal V' _{+ of the} battery unit 213. The fourth compensation current I _{comp4 flows} from the second port T2, flows through the switch 276 and the resistor 234, and flows to the negative terminal V' _{- of the} battery unit 213. In one embodiment, the third compensation current I _comp3 and the fourth compensation current I _comp4 are substantially equal to the third current I _cons3 and the fourth current I _{cons4 , respectively} . The measuring unit 240 measures the transfer voltage difference generated by the potential transfer circuit 220 proportional to the cell voltage of the battery cell 213. Further, the battery measuring circuit 200 obtains the cell voltage of the battery unit 213.

3 is a block diagram showing the structure of a battery measuring circuit 300 for measuring the cell voltage of a battery cell in a battery pack according to an embodiment of the invention. Figure 3 will be described in conjunction with Figure 2. The cell voltage of the battery cell 211 is measured by the battery measuring circuit 300 in FIG. 3 as an example. The cell voltages of other battery cells within battery pack 210 in Figure 2 can be measured in a similar manner.

As shown in FIG. 3, the potential transfer circuit 220 includes an amplifier (Operational Amplifier, OPA for short) 341 and an amplifier 342, and a resistor 331, a resistor 332, a resistor 333, and a resistor 334. The current generator 260 includes a current source 382 and a current source 384 to generate a first compensation current I _comp1 and a second compensation current I _comp2 . Current generator 260 also includes a switch 392 coupled in series with current source 384 for _disabling or enabling first compensation current _Icomp1 . The measuring unit 240 includes an Analog-to-Digital Converter (ADC) 352 and a control circuit 362. The analog/digital converter 352 converts the first transfer voltage difference V _O1 and the second transfer voltage difference V _O2 between the transfer terminal V _OUTP and the transfer terminal V _OUTN into a digital signal. The control circuit 362 controls the switch 392 in the current generator 260 to disable or enable the first compensation current I _comp1 and to determine the first transfer voltage difference V _O1 and the second transfer voltage according to the indication received from the analog/digital converter 352. The digital signal of the difference V _O2 calculates the cell voltage V _{CELL of the} battery cell 211.

In operation, when the switch 271 and the switch 273 are turned on, the battery unit 211 is selected. The potential transfer circuit 220 consumes the first current I _cons1 and the second current I _cons2 . The first current I _{cons1 flows} out from the positive terminal V _{+ of the} battery cell 211 and flows through the resistor 231, the switch 271, the resistor 331, the resistor 333, and the amplifier 341. The second current I _{cons2 flows} from the negative terminal V _{− of the} battery unit 211 and flows through the resistor 232 , the switch 273 , the resistor 332 , the resistor 334 , and the amplifier 342 .

The control circuit 362 controls the switch 392 is turned off, thus, the first compensation current I _comp1 is disabled, the second compensation current I _comp2 enabled. It is substantially equal to a second current _I cons2 In one embodiment, the second compensation current I _comp2 the potential of the transfer circuit 220 is consumed.

The amplifier 341 receives the preset reference voltage V _REF . In one embodiment, resistor 331 has the same resistance as resistor 332, and resistor 333 has the same resistance as resistor 334. The voltage difference between the transfer terminal V _OUTP and the transfer terminal V _OUTN is: V _OUTP -V _OUTN =K ×(V _T1 -V _T2 ) (8) where the constant K is: K=R ₃₃₃ /R ₃₃₁ (9)R ₃₃₃ is the resistance of the resistor 333, and R ₃₃₁ is the resistance of the resistor 331.

Accordingly, the potential transfer circuit 220 supplies the analog/digital converter 352 with a first transfer voltage difference V _O1 . The analog/digital converter 352 converts the first transfer voltage difference V _O1 into a first digital signal D1.

Control circuit 362 then controls switch 392 to conduct. Therefore, both the first compensation current I _comp1 and the second compensation current I _comp2 are enabled. Accordingly, the potential transfer circuit 220 supplies the analog/digital converter 352 with a second transfer voltage difference V _O2 . The analog/digital converter 352 converts the second transfer voltage difference V _O2 into a second digital signal D2. The control circuit 362 receives the first digital signal D1 and the second digital signal D2, and calculates the cell voltage V _CELL of the battery unit 211 accordingly.

4 is a block diagram showing the structure of a battery measuring circuit 400 for measuring a cell voltage of a battery cell in a battery pack according to another embodiment of the present invention. The circuit elements in FIG. 4 numbered the same as those in FIG. 3 have the same functions and will not be described again. Figure 4 will be described in conjunction with Figure 3.

As shown in FIG. 4, the potential transfer circuit 220 further includes a switch 422. By controlling the switch 422 during the measurement of the cell voltage V _CELL , the effect on the measurement of the cell voltage due to non-ideal factors of the circuit components can be reduced. Non-ideal factors include, for example, the on-resistance of the switches 271 and 273, the mismatch between the resistors 331 and 332, the mismatch between the resistors 333 and 334, and the input offset voltage of the amplifier 342.

More specifically, control circuit 362 controls switch 422 to alternately turn on and off. When the switch 422 is turned on, the measuring unit 240 measures the non-ideal factors of the switch 271, the switch 273, and the potential transfer circuit 220, and obtains the measurement result V _A correspondingly. When the switch 422 is turned off, the potential transfer circuit 220 receives the voltage difference between the first port T1 and the second port T2, and the measuring unit 240 obtains the measurement result V _B correspondingly. Advantageously, by subtracting the measurement V _A from the measurement V _B , the effect of the non-ideal factor on the cell voltage measurement can be reduced.

In operation, switch 271 and switch 273 are turned on to select battery unit 211. The control circuit 362 controls the switch 422 to be turned on, and controls the switch 392 to be turned off, at which time the first port T1 and the second port T2 are short-circuited. Accordingly, the first compensation current I _comp1 is disabled, the second compensation current I _comp2 enabled. Assuming that the second compensation current I _{comp2 is} substantially equal to the second current I _cons2 consumed by the potential transfer circuit 220, the voltage drop across the switch 273 is negligible. Further, assuming that the voltage drop across switch 271 is V _SW1 , the input offset voltage of amplifier 342 is V _OS1 .

Based on the first transfer voltage difference V _O1 and the second transfer voltage difference V _O2 , the control circuit 362 obtains the cell voltage V _{CELL of the} selected battery cell 211. As shown in FIG. 4, switch 422 is placed between node H and node S. Similar results can be achieved if switch 422 is placed between first port T1 and second port T2 (this connection is not shown in Figure 4). Advantageously, the battery measurement circuit 400 can more accurately measure the cell voltage V _{CELL by} reducing the effects of non-ideal factors on cell voltage measurements.

FIG. 5 is a schematic structural view of an equivalent circuit 500 when the switch 422 of FIG. 4 is turned on and the switch 392 is turned off. The circuit elements in FIG. 5 numbered the same as those in FIG. 4 have the same functions and will not be described again. Figure 5 will be described in conjunction with Figure 4. Analog / digital converter 352 through the measured transition voltage difference (V _OUTP -V _OUTN) to obtain a third voltage V _O1A difference between V _OUTP and transfer end V _OUTN. The third voltage difference V _O1A is: V _O1A = m ₁ × V _SW1 + n ₁ × V _OS1 + q ₁ × _ΔR × V _IN (10) where m ₁ , n ₁ and q ₁ are proportional coefficients, ΔR is the difference between the ratio R ₃₃₁ / R ₃₃₃ and the ratio R ₃₃₂ / R _334, V _iN 211 to the battery cell voltage V ₊ at the positive terminal. ΔR is caused by a mismatch between the resistor 331 and the resistor 332 and a mismatch between the resistor 333 and the resistor 334. In one embodiment, the third voltage difference V _O1A first compensation current I _comp1 indication is disabled, the second compensation current I _comp2 non-ideal factors can be induced (e.g., on-resistance of the switch input 271 and an amplifier 342 bias Shift voltage).

When the control circuit 362 controls the switch 422 and the switch 392 to be turned on, the first compensation current I _comp1 and the second compensation current I _comp2 are both enabled. At this time, the first port T1 and the second port T2 are short-circuited. Similarly, assuming that the voltage drop across switch 273 is negligible, the voltage drop across switch 271 is V _SW2 , the input offset voltage of amplifier 342 is V _OS2 , and the equivalent circuit when both switch 422 and switch 392 are turned on is shown in Figure 5. The circuit 500 is similar. In one embodiment, the input offset voltage V _{OS1 is} equal to the input offset voltage V _OS2 . The analog/digital converter 352 obtains a fourth voltage difference V _O2A by _measuring a voltage difference (V _OUTP -V _OUTN ) between the transfer terminal V _OUTP and the transfer terminal V _OUTN . The fourth voltage difference V _O2A is: V _O2A = m ₂ × V _SW2 + n ₂ × V _OS2 + q ₂ × ΔR × V _IN (12) where m ₂ , n ₂ and q ₂ are proportional coefficients. In one embodiment, the fourth voltage difference V _O2A indicating the first compensation and the second compensation current I _comp1 current I _comp2 non-ideal factors were induced energy (e.g., the input offset voltage switch 271 on-resistance and an amplifier 342 ).

FIG. 6 is a schematic diagram of an equivalent circuit 600 when both the switch 422 and the switch 392 of FIG. 4 are open. The circuit elements in FIG. 6 numbered the same as those in FIG. 4 have the same functions and will not be described again. Figure 6 will be described in conjunction with Figure 4. Analog / digital converter 352 through the measured transition voltage difference (V _OUTP -V _{OUTN) V} O1B measurement results obtained between V _OUTP and transfer end V _OUTN. The measurement result V _O1B is: V _O1B = V _O1 + m ₁ × V _SW1 + n ₁ × V _OS1 + q ₁ × _ΔR × V _IN (11) In one embodiment, the measurement result V _O1B indicates the first compensation current I _comp1 is disabled, the second compensation current I _comp2 non-ideal factors can be induced (e.g., on-resistance switch 271 and an amplifier input offset voltage 342) and the first transfer differential voltage V _O1. Correspondingly, the control circuit 362 obtains the first transfer voltage difference V _O1 by subtracting the third voltage difference V _O1A from the measurement result V _O1B , thereby reducing the on-resistance of the switch 271 and the input offset voltage of the amplifier 342 to measure the cell voltage. The impact.

The equivalent circuit when switch 422 is open and switch 392 is turned on is similar to circuit 600 shown in FIG. Similarly, the analog / digital converter 352 between the end of the transition voltage V _OUTP and V _OUTN terminal transfer difference (V _OUTP -V _{OUTN) V} O2B measurement results obtained through the measurement. The measurement result V _O2B is: V _O2B = V _O2 + m ₂ × V _SW2 + n ₂ × V _OS2 + q ₂ × _ΔR × V _IN (13) In one embodiment, the measurement result V _O2B indicates the first compensation current I _comp1 and the second compensation current I _comp2 are non-ideal factors can be induced (e.g., on-resistance switch 271 and an amplifier 342, an input offset voltage) and the voltage difference between the second transfer V _O2. Correspondingly, the control circuit 362 obtains the second transfer voltage difference V _O2 by subtracting the fourth voltage difference V _O2A from the measurement result V _O2B , thereby reducing the on-resistance of the switch 271 and the input offset voltage of the amplifier 342 to measure the cell voltage. The impact.

FIG. 7 is a block diagram showing the structure of a battery measuring circuit 700 for measuring the cell voltage of a battery cell in a battery pack according to still another embodiment of the present invention. As shown in FIG. 7, the amplifier 341 in the potential transfer circuit 220 monitors the first current I _cons1 .

As shown in FIG. 7, the current generator 260 generates a first compensation current I _comp1 and a second compensation current I _comp2 according to the monitoring current I _SEN . More specifically, the current generator 260 includes a current mirror composed of a metal oxide semiconductor field effect transistor 761 to a metal oxide semiconductor field effect transistor 763 and a metal oxide semiconductor field effect transistor 767 to a metal oxide semiconductor field effect transistor. A current mirror formed by 768 generates a first compensation current I _comp1 and a second compensation current I _{comp2 , respectively} . The monitoring current I _SEN flows through the metal oxide semiconductor field effect transistor 761. Therefore, the first compensation current I _comp1 flowing through the metal oxide semiconductor field effect transistor 767 and the current I ₇₆₃ flowing through the metal oxide semiconductor field effect transistor 763 are proportional to the monitoring current I _SEN . In one embodiment, current I _{763 is} substantially equal to first current I _cons1 .

Current generator 260 also includes an amplifier 764, a metal oxide semiconductor field effect transistor 765, and a resistor 766. In one embodiment, the resistance of resistor 766 is equal to the resistance of resistor 333 and resistor 334. By combining equations (8) and (9), the current I _CELL flowing through the metal oxide semiconductor field effect transistor 765 is: I _CELL = (V _OUTP - V _OUTN ) / R ₇₆₆ = (V _T1 - V _T2 /R ₃₃₁ (14) where R ₇₆₆ is the resistance of resistor 766.

The first current I _cons1 is substantially equal to (V _T1 -V _OUTN ) / (R ₃₃₁ +R ₃₃₃ ), and the second current I _cons2 is substantially equal to (V _T2 -V _OUTP ) / (R ₃₃₂ +R ₃₃₄ ). Then, the difference between the first current I _cons1 and the second current I _cons2 is: I _cons1 -I _cons2 =(V _T1 -V _OUTN )/(R ₃₃₁ +R ₃₃₃ )-(V _T2 -V _OUTP )/(R ₃₃₂ +R ₃₃₄ )=[(V _T1 -V _T2 )+(V _OUTP -V _OUTN )]/(R ₃₃₁ +R ₃₃₃ )=(V _T1 -V _T2 )/R ₃₃₁ (15) Permeation equation (14) And equation (15), the second current I _cons2 is: I _cons2 =I _cons1 -I _CELL (16) Therefore, the second compensation current I _comp2 is equal to I ₇₆₃ -I _CELL , which is equal to I _cons1 -I _CELL That is, the second compensation current I _comp2 is equal to the second current I _cons2 .

FIG. 8 is a schematic view showing the structure of an amplifier 341 including a Metal Oxide-Semiconductor Field Effect Transistor (MOSFET) in FIG. Figure 8 will be described in conjunction with Figure 7. The metal oxide semiconductor field effect transistor is shown in FIG. 8. Port V _DD and port V _SS are the power supply voltage ports of the amplifier 341, and the ports V _BP and V _BN are the bias voltage ports. The metal oxide semiconductor field effect transistor 801, the metal oxide semiconductor field effect transistor 802, the metal oxide semiconductor field effect transistor 803, and the metal oxide semiconductor field effect transistor 804 constitute a current mirror. In one embodiment, the current flowing through port IO is proportional to the current flowing through port OUT. The first current I _cons1 in FIG. 7 flows through the resistor 333 and flows into the port OUT of the amplifier 341. Accordingly, the monitoring current I _SEN flowing into the port IO in FIG. 7 monitors the first current I _cons1 and is proportional to the first current I _cons1 .

9 is a flow chart 900 of a battery measurement method for measuring a cell voltage of a battery cell within a battery pack, in accordance with one embodiment of the present invention. Figure 9 will be described in conjunction with Figures 2-8.

In step 902, a battery unit (eg, battery unit 211) is selected.

In step 904, the measurement circuit consumes the first current and the second current. The first current flows from the positive terminal of the selected battery cell, flows through the first resistor, and flows to the first port. The second current flows from the negative terminal of the selected battery cell, flows through the second resistor, and flows to the second port. For example, the measurement circuit consumes the first current I _cons1 and the second current I _cons2 . The first current I _{cons1 flows} out from the positive terminal V _{+ of the} battery unit 211 , flows through the resistor 231 and the switch 271 , and flows to the first port T1 . The second current I _{cons2 flows} from the negative terminal V _{− of the} battery unit 211 , flows through the resistor 232 and the switch 273 , and flows to the second port T2 .

In step 906, a first compensation current is generated according to the first current, and a second compensation current is generated according to the second current. The first compensation current flows from the positive terminal of the selected battery cell, flows through the first resistor, and flows to the first port. The second compensation current flows from the second port, flows through the second resistor, and flows to the negative terminal of the selected battery unit. For example, if the selected cell 211, a first compensation current is generated in accordance with a first current I _{comp1 I} cons1. The first compensation current I _comp1 flows from the positive terminal V ₊ , flows through the resistor 231 and the switch 271, and flows to the first port T1. At the same time, generating a second compensation current I _comp2 According to a second current _I cons2. The second compensation current I _comp2 flows out from the second port T2, flows through the switch 273 and the resistor 232, and flows to the negative terminal V ₋ . In one embodiment, the first compensation current I _{comp1 is} proportional to the first current I _cons1 and the second compensation current I _comp2 is substantially equal to the second current I _cons2 .

In step 908, when the first compensation current is disabled, the measurement circuit receives a first voltage difference between the first port and the second port, and when the first compensation current is enabled, the measurement circuit receives the first port and the second port. The second voltage difference between. More specifically, when the first compensation current is disabled, a first voltage drop is generated on the first resistor, and when the first compensation current is enabled, a second voltage drop is generated on the first resistor. The first voltage difference indicates a difference between a cell voltage of the selected battery cell and a first voltage drop. The second voltage difference indicates a difference between a cell voltage of the selected battery cell and a second voltage drop. The measurement circuit also provides a first transfer voltage difference indicative of the first voltage difference and a second transfer voltage difference indicative of the second voltage difference.

For example, the first compensation current I _comp1 except when enabled, generates a first voltage drop across the resistor 231 V _DROP1. The measuring circuit receives the first voltage difference V _DIFF1 between the first port T1 and the second port T2. The first voltage difference V _DIFF1 indicates a difference between the cell voltage V _{CELL of the} battery cell 211 and the first voltage drop V _DROP1 . Correspondingly, the measuring circuit provides a first transfer voltage difference V _O1 between the transfer terminal V _OUTP and the transfer terminal V _OUTN . The first transfer voltage difference V _O1 indicates the first voltage difference V _DIFF1 . When the first compensation current I _{comp1 is} enabled, a second voltage drop V _DROP2 is generated across the resistor 231. The measurement circuit receives a second voltage difference V _DIFF2 between the first port T1 and the second port T2. The second voltage difference V _DIFF2 indicates the difference between the cell voltage V _CELL and the second voltage drop V _DROP2 . Correspondingly, the measuring circuit provides a second transfer voltage difference V _O2 between the transfer terminal V _OUTP and the transfer terminal V _OUTN . The second transfer voltage difference V _O2 indicates the second voltage difference V _DIFF2 .

In step 910, the measurement circuit calculates a cell voltage of the selected battery cell based on the first voltage difference and the second voltage difference. More specifically, the measurement circuit calculates a third voltage proportional to the first transfer voltage difference and subtracts the second transfer voltage difference from the third voltage. For example, the measurement circuit calculates a third voltage V _O3 that is proportional to the first transfer voltage difference V _O1 . By subtracting the second transfer voltage difference V _O2 from the third voltage V _O3 , the cell voltage V _{CELL of the} selected battery cell can be obtained. That is, the measuring circuit calculates the cell voltage V _{CELL of the} selected battery cell based on the proportional coefficient between the second voltage drop V _DROP2 and the first voltage drop V _DROP1 .

FIG. 10 is a block diagram showing the structure of a battery measuring circuit 1000 for measuring a cell voltage of a battery cell in a battery pack according to still another embodiment of the present invention. Elements in Figure 10 that have the same reference numerals as in Figure 2 have the same or similar functions.

Battery measurement circuit 1000 includes battery pack 210, resistor bank 230, capacitor bank 280, switch bank 270, current generator 1060, and measurement circuitry. The measurement circuit includes a potential transfer circuit 220 and a measurement unit 1040. Battery measurement circuit 1000 also includes dual junction transistor 101 and dual junction transistor 102. When the battery unit 211 is selected, the double junction transistor 101 and the double junction transistor 102 can reduce the influence of the current I _cons10 and the current I _cons20 on the cell voltage measurement. The resistor 103 and the resistor 104 are used to generate a bias voltage between the base and the emitter of the double junction transistor 101 and the double junction transistor 102. More specifically, when the battery unit 211 is selected, it is assumed that the current flowing through the resistor 103 and the resistor 104 is negligible, and the current I _cons10 and the current I _{cons20 are the bases} of the double junction transistor 101 and the double junction transistor 102. The current flowing into the potential transfer circuit 220 is the emitter current of the double junction transistor 101 and the double junction transistor 102. For a double junction transistor, the base current is less than the emitter current. Therefore, the current I _cons10 and the current I _{cons20 are} smaller than the current flowing into the potential transfer circuit 220. In one embodiment, current I _cons10 and current I _cons20 may be ignored, so that the voltage drop across resistor 231 and the voltage drop across resistor 232 are also negligible. The potential transfer circuit 220 receives the voltage difference between the first port T1 and the second port T2 and provides a transfer voltage difference proportional to the cell voltage of the selected battery cell 211. The measuring unit 1040 measures the transfer voltage difference generated by the potential transfer circuit 220. Thus, the battery measuring circuit 1000 obtains the cell voltage V _{CELL of the} battery cell 211. The manner in which the battery measuring circuit 1000 measures the cell voltages of the battery cells 212 and the battery cells 213 is similar to the manner in which the battery measuring circuit 200 in FIG. 2 measures the cell voltages of the battery cells 212 and the battery cells 213. That is, similar to the current generator 260 of FIG. 2, when the cell voltages of the battery cells 212 and the battery cells 213 are measured, the current generator 1060 generates a compensation current. However, when the cell voltage of the battery cell 211 is measured, since the current consumed by the potential transfer circuit 220 is negligible, the current generator 1060 does not generate the first compensation current I _comp1 and the second compensation current I _comp2 .

The above detailed description and the accompanying drawings are only typical embodiments of the invention. It is apparent that various additions, modifications and substitutions are possible without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood by those of ordinary skill in the art that the present invention may be applied in the form of the form, structure, arrangement, ratio, material, element, element, and other aspects in the actual application without departing from the invention. Changed. Therefore, the embodiments disclosed herein are intended to be illustrative and not limiting, and the scope of the invention is defined by the scope of the appended claims and their legal equivalents.

200‧‧‧Battery measurement circuit

210‧‧‧Battery Pack

211~213‧‧‧ battery unit

220‧‧‧potentiometric transfer circuit

230‧‧‧resistance group

231~234‧‧‧resistance

240‧‧‧Measurement unit

260‧‧‧current generator

270‧‧‧ switch group

271~276‧‧‧ switch

280‧‧‧capacitor group

282, 284, 286‧‧ ‧ capacitor

Claims (17)

A battery measuring circuit comprising: a measuring circuit comprising: a first port coupled to a positive terminal of a battery unit via a first resistor; and a second port coupled to the battery unit via a second resistor a negative terminal, wherein the measuring circuit consumes a first current and a second current, the first current flows from the positive terminal, flows through the first resistor, and flows to the first port, and the second current flows from the negative a current flowing out through the second resistor to the second port; and a current generator coupled to the battery unit, generating a first compensation current according to the first current, the first compensation current flowing from the positive terminal And flowing through the first resistor to the first port, wherein when the first compensation current is disabled, the measuring circuit receives a first voltage difference between the first port and the second port; the first compensation When the current is enabled, the measuring circuit receives a second voltage difference between the first port and the second port; the measuring circuit calculates a cell voltage of the battery unit according to the first voltage difference and the second voltage difference, Among them, the first When the compensation current is disabled, a first voltage drop is generated on the first resistor, and when the first compensation current is enabled, a second voltage drop is generated on the first resistor, and the measuring circuit is configured according to the second voltage drop. A ratio of the first voltage drop is calculated for the cell voltage. The battery measuring circuit of claim 1, wherein the first compensation current is proportional to the first current. The battery measuring circuit of claim 1, wherein the measuring circuit further comprises a potential transfer circuit, and if the first compensation current is disabled, the potential transfer circuit provides a first transfer voltage indicating the first voltage difference Poor; if the first compensation current is enabled, the potential transfer circuit provides a second transfer voltage difference indicative of the second voltage difference. The battery measuring circuit of claim 3, wherein the measuring circuit calculates a third voltage proportional to the first transfer voltage difference, and subtracts the second transfer voltage difference from the third voltage to Calculate the cell voltage. The battery measuring circuit of claim 3, wherein the potential transfer circuit comprises an amplifier, the amplifier generates a monitoring current according to the first current, and receives a preset reference voltage, the current generator is configured according to the monitoring current The first compensation current is generated. The battery measuring circuit of claim 1, wherein the first port is short-circuited with the second port and the first compensation current is disabled, the measuring circuit measures a third voltage difference; the first port and the first port When the second port is short-circuited and the first compensation current is enabled, the measuring circuit measures a fourth voltage difference, and the measuring circuit calculates the cell voltage according to the third voltage difference and the fourth voltage difference. The battery measuring circuit of claim 1, wherein the current generator generates a second compensation current according to the second current, the second compensation current flows out from the second port, flows through the second resistor, and flows The negative end. The battery measuring circuit of claim 1, wherein the measuring circuit further comprises an analog/digital converter, wherein the analog/digital converter converts a signal indicating the first voltage difference and the second voltage difference into one A digital signal, the measuring circuit calculates the cell voltage based on the digital signal. A battery measuring system comprising: a plurality of battery units; a plurality of resistors coupled to the plurality of battery cells; a measuring circuit comprising: a first port, coupled to a first one of the plurality of battery cells through a first one of the plurality of resistors And a second port coupled to a negative end of the first battery unit through a second resistor of the plurality of resistors, wherein the measuring circuit consumes a first current and a second current, the first a current flowing from the positive terminal, flowing through the first resistor, to the first port, the second current flowing from the negative terminal, flowing through the second resistor, to the second port; and a current generator, Coupling the plurality of battery cells, generating a first compensation current according to the first current; flowing the first compensation current from the positive terminal, flowing through the first resistor, to the first port; wherein the first compensation When the current is dissipated, a first voltage drop is generated on the first resistor, and when the first compensation current is enabled, a second voltage drop is generated on the first resistor, and the measuring circuit is configured according to the first voltage drop and the first voltage drop Two voltage drops are calculated for one of the first battery cells a voltage voltage, wherein the measurement circuit receives a first voltage difference indicating a difference between the cell voltage and the first voltage drop, and receives a difference indicating a difference between the cell voltage and the second voltage drop The second voltage difference, the measuring circuit calculates the cell voltage according to the first voltage difference and the second voltage difference. The battery measuring system of claim 9, wherein the first compensation current is proportional to the first current. The battery measuring system of claim 9, wherein the measuring circuit further comprises a potential transfer circuit, and if the first compensation current is disabled, the potential is turned The shift circuit provides a first transfer voltage difference indicative of the first voltage difference; and if the first compensation current is enabled, the potential transfer circuit provides a second transfer voltage difference indicative of the second voltage difference. The battery measuring system of claim 11, wherein the measuring circuit calculates a third voltage proportional to the first transfer voltage difference, and subtracts the second transfer voltage difference from the third voltage to Calculate the cell voltage. The battery measuring system of claim 9, wherein the current generator generates a second compensation current according to the second current, the second compensation current flows out from the second port, flows through the second resistor, and flows The negative end. A battery measuring method includes: consuming a first current and a second current, wherein the first current flows from a positive end of a battery unit, flows through a first resistor, and flows to a first port, the second Current flows from a negative terminal of the battery unit, flows through a second resistor, and flows to a second port; and generates a first compensation current according to the first current, the first compensation current flows out from the positive terminal, and flows through the current The first resistor flows to the first port; when the first compensation current is disabled, receiving a first voltage difference between the first port and the second port; when the first compensation current is enabled, receiving the first a second voltage difference between the port and the second port; and calculating a cell voltage according to the first voltage difference and the second voltage difference, wherein when the first compensation current is disabled, the first resistor generates a a first voltage drop; a second voltage drop is generated on the first resistor when the first current is enabled, the battery measurement method further comprising calculating the unit according to a ratio of the second voltage drop to the first voltage drop Voltage. The battery measuring method of claim 14, wherein the first voltage difference indicates a first difference between the cell voltage and the first voltage drop, The second voltage difference is indicative of a second difference between the cell voltage and the second voltage drop. The battery measuring method of claim 14, wherein the step of calculating the cell voltage based on the first voltage difference and the second voltage difference after the step of receiving the first voltage difference and the second voltage difference Previously, the battery measuring method further includes: providing a first transfer voltage difference indicating the first voltage difference and providing a second transfer voltage difference indicating the second voltage difference. The battery measuring method of claim 16, wherein the battery is provided after the step of providing the first transfer voltage difference indicating the first voltage difference and providing the second transfer voltage difference indicating the second voltage difference The measuring method further includes: calculating a third voltage proportional to the first transfer voltage difference; and subtracting the second transfer voltage difference from the third voltage.