JP3563528B2 - Abnormality detector and constant current power supply using the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an abnormality detection device that detects an abnormality in a constant current source or a load based on a load current of a constant current source, and detects an abnormality in the constant current source or a load and outputs a constant current based on the abnormality detection. The present invention relates to a constant current power supply device that can be stopped.
[0002]
[Prior art]
As a constant current power supply device configured to be able to supply a constant current having a value obtained by multiplying a voltage value of an input reference input signal by a predetermined gain to a load, a constant current power supply device shown in FIG. 5 is conventionally known. The constant current power supply 51 shown in FIG. 1 functions as a voltage-current converter, and includes a subtraction circuit 11, an amplification circuit 12, a current amplification circuit 13, and a current detection resistor 14 functioning as a so-called error amplification circuit. It has.
[0003]
In the constant current power supply 51, the reference input signal V_refIs input to the subtraction circuit 11, the amplification circuit 12 and the current amplification circuit 13_refIs supplied to the load 2 via the connection terminal 21 and the load-side connection terminal 22. When a current flows through the load 2, the resistor 14 detects the load current value, and the subtraction circuit 11_refAnd the difference voltage V between the detected voltage and the detected voltage corresponding to the load current detected by the resistor 14._SIs output to the amplifier circuit 12. As a result, the amplifier circuit 12 and the current amplifier circuit 13 output the reference input signal V_refIs controlled to supply a constant current of a value obtained by multiplying the voltage value by a predetermined gain to the load 2.
[0004]
[Problems to be solved by the invention]
However, the conventional constant current power supply 51 has the following problems. That is, the connection terminal 21 on the output side of the current amplification circuit 13 and the connection terminal 22 on the load side of the load 2 may be in poor contact, the connection between the connection terminals 21 and 22 may be open, or the current amplification circuit 13 may be disconnected. In the case of a failure or an abnormal state, a constant current does not flow through the load 2. Therefore, the voltage between both ends of the resistor 14 becomes 0V. In this case, the subtraction circuit 11 determines whether the constant current does not flow due to the abnormality,_refSince it is not possible to determine whether the load current has decreased due to the decrease in the voltage value, the amplifier 2 and the current amplifier 13 are controlled to cause a constant current to flow through the load 2. As a result, the current amplifying circuit 13 outputs the positive cycle reference input signal V_refIs amplified, the amplitude is + V which is the positive side power supply voltage._CCWhen the voltage which has reached the maximum output voltage is output and the signal in the negative cycle is amplified, the negative side power supply voltage -V_CCIs output. As a result, there is a problem that the contact and the non-contact are repeated between the connection terminal 21 and the load-side connection terminal 22 to cause a spark, and in some cases, the current amplification circuit 13 and the load 2 are broken. Further, when the load-side connection terminal 22 is disconnected, a high voltage is applied to the connection terminal 21, which may cause an electric shock if touched by a hand, which is dangerous.
[0005]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an abnormality detection device that can detect an abnormality based on a voltage value of a reference input signal and a load current value. It is another object of the present invention to provide a constant current power supply device capable of stopping output of a constant current by detecting an abnormality.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the abnormality detection device according to the first aspect of the present invention provides a load current value of a constant current source configured to supply a constant current of a value obtained by multiplying a voltage value of a reference input signal by a predetermined gain to a load. Load current detecting means for detecting the actual gain of the constant current source based on at least the detected load current value and the voltage value of the reference input signalReciprocal ofGain variable detection means for detecting a gain variable approximated toTo the reciprocal of the profitAbnormality determining means for outputting an abnormality signal for detecting abnormality of the constant current source or the load based on the approximated reference gain variable and the detected gain variable.The gain variable detection means includes a division circuit that outputs a gain variable by dividing the voltage value of the reference input signal by the load current value, and the abnormality determination means determines that the gain variable output from the division circuit corresponds to the gain variable. A comparator that outputs an abnormal signal when it is larger than the reference gain variableIt is characterized by having. in this case,In this specification, the “load” is a concept including all devices connected to the output side of the constant current source. Further, “a reference gain variable corresponding to a gain variable and approximated to one of a predetermined gain and its reciprocal” refers to a reference gain variable approximating a predetermined gain when the gain variable is approximated to an actual gain. When the gain variable is approximated to the reciprocal of the actual gain, it refers to the reference gain variable that approximates the reciprocal of the predetermined gain. Further, the division circuit can be constituted by an analog division circuit or a digital division circuit.
[0007]
In this abnormality detecting device, the constant current source normally supplies a constant current having a value obtained by multiplying the voltage value of the reference input signal by a predetermined gain to the load. The variable is substantially equal to the reference gain variable corresponding to the gain variable regardless of the level of the voltage value of the reference input signal. For this reason, the abnormality determination means can determine that there is no abnormality in the load. On the other hand, when any abnormality occurs in the constant current source, the load, or the like, the gain of the constant current source generally decreases. Therefore, the gain variable detected by the gain variable detecting means has a value different from the reference gain variable. For this reason, the abnormality determination means outputs an abnormality signal on the basis of the gain variable and the reference gain variable, assuming that an abnormality has occurred. As described above, unlike the case where the abnormality is simply detected based on the load current, the abnormality is determined based on the gain variable and the reference gain variable. Therefore, whether the abnormality has occurred or the voltage value of the reference input signal decreases. Thus, it is possible to reliably determine whether the load current has decreased. As a result, for example, by stopping the constant current operation of the constant current source based on the abnormal signal, it is possible to prevent breakage of the constant current source and the load and to avoid a dangerous situation due to the output voltage of the constant current source. Can be.
[0008]
Also,In this abnormality detection device, the division circuit outputs a gain variable by dividing the voltage value of the reference input signal by the load current value. In this case, since the gain of the constant current source generally decreases due to a decrease in the load current in the event of an abnormality, the abnormality determining means uses the constant current source based on the reference gain variable and the gain variable of the division circuit. It is possible to easily determine whether an abnormality has occurred in the load or the load. Note that by performing division by the division circuit, for example, when the load is released, the gain variable, which is the reciprocal of the actual gain, rapidly increases, so that the abnormality can be determined more easily.
[0009]
Claim2The described abnormality detection device,Load current detection means for detecting a load current value of a constant current source configured to be able to supply a constant current having a value obtained by multiplying a voltage value of a reference input signal by a predetermined gain to a load, and at least the detected load current value and Gain variable detection means for detecting a gain variable approximated to the reciprocal of the actual gain of the constant current source based on the voltage value of the reference input signal; and a reference gain variable corresponding to the gain variable and approximated to a reciprocal of a predetermined gain. An abnormality determination unit that outputs an abnormality signal for detecting an abnormality of the constant current source or the load based on the detected gain variable,The gain variable detection means includes: an addition circuit that adds a predetermined constant to the load current value; and a division circuit that divides at least the voltage value of the reference input signal by the added current value to output the divided value as a gain variable. The determining means is obtained by dividing at least the voltage value of the reference input signal by an addition current value obtained by adding a predetermined constant to a load current value at a predetermined gain, and the gain variable output from the division circuit is obtained. Outputting an abnormal signal when the value is larger than a corresponding reference gain variable.To.
[0010]
In this abnormality detection device, the constant current source normally supplies a constant current having a value obtained by multiplying the voltage value of the reference input signal by a predetermined gain to the load. The variable is substantially equal to the reference gain variable corresponding to the gain variable regardless of the level of the voltage value of the reference input signal. For this reason, the abnormality determination means can determine that there is no abnormality in the load. On the other hand, when any abnormality occurs in the constant current source, the load, or the like, the gain of the constant current source generally decreases. Therefore, the gain variable detected by the gain variable detecting means has a value different from the reference gain variable. For this reason, the abnormality determination means outputs an abnormality signal on the basis of the gain variable and the reference gain variable, assuming that an abnormality has occurred. As described above, unlike the case where the abnormality is simply detected based on the load current, the abnormality is determined based on the gain variable and the reference gain variable. Therefore, whether the abnormality has occurred or the voltage value of the reference input signal decreases. Thus, it is possible to reliably determine whether the load current has decreased. As a result, for example, by stopping the constant current operation of the constant current source based on the abnormal signal, it is possible to prevent the constant current source and the load from being damaged, and Dangerous situations due to the output voltage of the flow source can be avoided.
[0011]
Also,For example, when the constant current source outputs an AC constant current, the load current value detected by the load current detecting means is 0 A twice in one cycle of the reference input signal. Therefore, in the division by the division circuit, since the division is performed by the value 0, an error may occur in the gain variable. Therefore, in this abnormality detection device, the adding circuit adds a predetermined constant to the load current value, and the dividing circuit divides the voltage value of the reference input signal by the added current value. As a result, since there is no division by the value 0, no error occurs in the gain variable of the division circuit. Therefore, the abnormality determination means determines that the gain variable of the division circuit is a reference obtained by dividing the voltage value of the reference input signal by an addition current value obtained by adding a predetermined constant to a load current value when the constant current source outputs the predetermined gain. When it is larger than the gain variable, it is possible to output an abnormal signal assuming that an abnormality has occurred.
[0012]
Claim3The abnormality detection device described in the claims2In the abnormality detection device described above, the division circuit is configured to add a value obtained by adding a voltage value of the reference input signal to a division value obtained by dividing a predetermined constant by an actual gain obtained by dividing a voltage value of the reference input signal by a load current value. By dividing by the added current value, it is output as a gain variable.Based on the gain variableAn abnormal signal is output when the value is larger than the quasi-gain variable.
[0013]
In this abnormality detection device, the division circuit divides the value obtained by adding the voltage value of the reference input signal to the division value obtained by dividing the predetermined constant by the actual gain by the addition current value of the addition circuit. As a result, the division value output from the division circuit becomes equal to the gain variable which is the reciprocal of the actual gain. For this reason, the reference gain variable can be fixed to the reciprocal of the predetermined gain or a voltage slightly higher than the predetermined gain. As a result, the division by the abnormality determining means becomes unnecessary, and thereby, it is possible to determine whether or not an abnormality has occurred. It can be performed at high speed.
[0014]
Claim4The abnormality detection device described in claim 13The abnormality detection device according to any one of the above, further comprising: a duty ratio determination unit that inputs an abnormality signal and outputs a new abnormality signal when a duty ratio of one cycle of the reference input signal of the abnormality signal is larger than a predetermined duty ratio. It is further characterized by being provided.
[0015]
The constant current source may distort the output voltage waveform near the maximum amplitude of the reference input signal when the load impedance is somewhat high even during normal operation. In such a case, since the gain variable detected by the gain variable detecting means becomes a gain variable at the time of abnormality, the abnormality determining means may output an abnormal signal on the assumption that an abnormality has occurred. Even in such a case, in the abnormality detection device, the duty ratio determination circuit outputs the abnormality signal only when the duty ratio is larger than, for example, an allowable range of a predetermined duty ratio. As a result, it is possible to prevent the abnormal signal from being output frequently during normal operation.
[0016]
Claim5The constant current power supply according to claim 14And a constant current source configured to stop output of a constant current by an abnormality signal output from the abnormality detection device.
[0017]
In this constant current power supply device, the control means stops the output of the constant current to the constant current source by outputting an abnormal signal based on the gain variable and the reference gain variable. Therefore, damage to the constant current source and the load can be prevented, and a dangerous situation due to the output voltage of the constant current source can be avoided.
[0018]
Claim6The constant current power supply described in claim5In the constant current power supply device described above, a feedback control unit that controls the load current value to be constant based on a detected voltage corresponding to the detected load current value and a reference input signal is provided.
[0019]
In this constant current power supply device, it is assumed that an abnormality has occurred when the feedback control means controls to keep the load current value constant based on the detected voltage and the reference input signal corresponding to the detected load current value. The control means stops the output of the constant current from the constant current source. For this reason, in the conventional constant current power supply device 51, it is determined whether an abnormality occurs and the constant current does not flow, or whether the reference input signal V_refSince it is not possible to determine whether the load current has decreased due to the decrease in the voltage value of the load 2, the current amplifier circuit 13 and the load 2 may be destroyed by controlling the constant current to flow through the load 2. On the other hand, in the constant current power supply device, such a situation can be reliably avoided.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which an abnormality detection device and a constant current power supply device according to the present invention are applied to a power supply device that outputs a high-voltage constant current will be described with reference to the accompanying drawings. In the following, the same components as those of the conventional constant current power supply device 51 are denoted by the same reference numerals, and redundant description will be omitted.
[0021]
FIG. 1 is a block diagram of a power supply device 1 capable of supplying a high-voltage constant current DC of DC 200 V to a load, for example. Hereinafter, the configuration of the power supply device 1 will be described in detail.
[0022]
The power supply 1 has a reference input signal V_refAnd a load current detection voltage V corresponding to a load current flowing through the load 2._IDifference voltage V_S, A subtraction circuit (feedback control means) 11 functioning as an error amplification circuit for controlling the load current value to be constant, and a difference voltage V from the subtraction circuit 11._SBased on the reference input signal V_refCircuit 12 and a current amplifying circuit 13 for supplying a constant current of a value obtained by multiplying a predetermined gain G to the load 2 and a resistor for detecting a load current value(Load current detection means)14 and an analog division circuit (gain variable detection means), Division circuit) 15 and an abnormality detection unit (abnormality determination means) 16 for detecting an abnormality.Note that the analog division circuit 15 and the abnormality detection unit 16 constitute an abnormality detection device according to the present invention, and the subtraction circuit 11, the amplifier circuit 12, and the current amplifier circuit 13 constitute a constant current source according to the present invention.
[0023]
The analog division circuit 15 is configured by modifying a multiplication circuit of a known circuit, and includes a load current detection voltage V detected by the resistor 14._IWith the voltage value (equivalent to the load current value) when the resistor 14 is a 1-ohm resistor, and the reference signal V_ref, That is, the reference signal V of the power supply 1_refThe reciprocal (1 / Gr) of the actual gain Gr, which is the conversion gain to the load current with respect to the voltage of_GAnd output.
[0024]
The abnormality detection unit 16StandardA voltage output circuit 17 and a comparator 18 are provided. The reference voltage output circuit 17 is a voltage slightly higher than the voltage corresponding to the reciprocal of the gain G during normal operation (hereinafter, referred to as “normal operation”) in which the power supply device 1 operates at the gain G, that is, the analog voltage. Gain variable voltage V output by division circuit 15 during normal operation_GThe reference gain variable voltage V is a voltage slightly higher than the reference gain variable._GrIs output as Further, the comparator 18 calculates the gain variable voltage V output from the analog division circuit 15._GAnd the reference gain variableVoltageV_GrAnd the gain variable voltage V_GIs the reference gain variableVoltageV_GrIs larger than the abnormal signal S_AIs output to the current amplification circuit 13 and a monitoring device (not shown). In the power supply device 1, if there is a contact failure between the connection terminal 21 and the load-side connection terminal 22, the constant current is not supplied to the load 2. Departing from the linear region of the conversion is lower than the gain G. In such a case, the abnormality detection unit 16 determines that the abnormality has occurred and outputs the abnormality signal S._AIs output.
[0025]
Next, the operation of the power supply device 1 will be described with reference to FIG.
[0026]
During normal operation, when a constant current is supplied from the power supply device 1, the load current detection voltage V_IIs controlled to a constant value by the subtraction circuit 11 as shown by the DC load current waveform 41 in FIG. In this state, the power supply 1 receives the reference signal V_refIs supplied to the load 2 by multiplying the gain value by the gain value of the reference voltage V._refGain variable voltage V output from analog divider circuit 15 regardless of the level of_GIs output from the reference voltage output circuit 17Reference gain variable voltage V _Gr Is lower than the voltage value. Therefore, the comparator 18 outputs the abnormal signal S_AIs not output. Therefore, in the power supply device 1, the difference voltage V_SIs controlled so that the gain of the power supply device 1 becomes the value G.
[0027]
On the other hand, if any abnormality occurs on the load 2 side due to a poor contact between the connection terminal 21 and the load-side connection terminal 22 or an increase in the load impedance of the load 2, the actual gain Gr of the power supply device 1 decreases. Therefore, as shown by the DC load current waveform 42 in FIG._IVoltage value drops sharply. In the figure, the DC load current waveform 42 is drawn with a gentle slope for easy understanding. In this case, the gain variable voltage V output from the analog division circuit 15_GIs the reference gain variable voltage V_GrVoltage value. Therefore, the comparator 18 outputs the high-level abnormal signal S_AIs output. As a result, the current amplification circuit 13 outputs the abnormal signal S_AIs input, the output of the constant current is stopped (refer to the DC load current waveform 43 in the figure). At the same time, the abnormal signal S_AAllows the monitoring device connected to the outside of the device to detect that the load 2 has failed.
[0028]
As described above, according to the power supply device 1, when an abnormality occurs on the load 2 side or the like and the actual gain Gr of the power supply device 1 decreases, the output of the constant current to the current amplifier circuit 13 can be stopped. As a result, the destruction of the current amplification circuit 13 and the load 2 can be reliably prevented, and a dangerous state can be avoided because high-voltage direct current is not output to the connection terminal 21.
[0029]
Then figure2With reference to, another embodiment in which the abnormality detection device and the constant current power supply device according to the present invention are applied to a power supply device 31 that outputs an AC constant current will be described. Note that the same components as those of the power supply device 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0030]
The power supply 31 receives the reference input signal V_refTo a maximum amplitude voltage of 200 Vp-p and output an AC power of a maximum output power of 1 KVA. As shown in the figure, in addition to the configuration of the power supply device 1, an offset voltage output circuit is provided. 32, an addition circuit 33, and a duty ratio determination circuit (duty ratio determination means) 36._GrUnlike the reference gain variable voltage V as the reference variable_Gr1Is provided.Note that the analog division circuit 15, the offset voltage output circuit 32, the addition circuit 33, the abnormality detection unit 34, and the duty ratio determination circuit constitute an abnormality detection device according to the present invention.
[0031]
The offset voltage output circuit 32 outputs an offset voltage V which is a voltage value appearing at a resistor having a resistance value of 1 ohm when the power supply device 1 passes a predetermined current through the resistor._O(Predetermined constant) can be output.
[0032]
The adder circuit 33 detects the load current detection voltage V_IIs converted to a voltage value when the resistor 14 is a 1-ohm resistor, and the offset voltage V_OIs the added voltage V of the value obtained by adding_AIs output to the analog division circuit 15.
[0033]
The reference voltage output circuit 35 outputs the reference gain variable voltage V_Gr1And outputs a reference gain variable voltage V_Gr1Is the load current detection voltage V during normal operation. _I Is converted to a voltage value when the resistor 14 is a 1-ohm resistor, and the offset voltage V_O(Predetermined constant) is added to the reference signal V_refVoltage corresponding to the value obtained by dividing the voltage value of(Gain variable voltage V _G1 )The voltage is set slightly higher than the voltage. Note that the reference gain variable voltage V_Gr1Is the load current detection voltage V during normal operation. _I Offset voltage V_OIs added to the reference gain variable voltage V in the power supply device 1._GrSince the voltage value is slightly lower than that, the voltage may be set in advance to allow for the voltage value.
[0034]
The duty ratio determination circuit 36 detects the abnormal signal S even when the impedance of the load 2 becomes slightly higher and the power supply device 1 partially distorts the output voltage waveform._ABlock the output of This duty ratio determination circuit 36 outputs the reference signal V_refFor one cycle of the power supply device 31, the time during which the reduction of the actual gain Gr of the power supply_refIs stored as a reference duty ratio, which allows the actual gain Gr to be reduced with respect to one cycle of the abnormal signal S._AReference signal V_refIs higher than the reference duty ratio when the duty ratio with respect to one cycle is higher than the reference duty ratio, a new abnormal signal S having a continuous high level_A1Is output.
[0035]
Next, the operation of the power supply device 31 will be described with reference to FIG.4This will be described with reference to FIG. The detailed description of the same operation as that of the power supply device 1 is omitted.
[0036]
During normal operation, the reference input signal V_refWhen a constant current having a value obtained by multiplying the maximum amplitude by the gain G is supplied from the power supply device 31, the load current detection voltage V_IIs the reference signal V_refIn this state, the comparator 18 outputs the abnormal signal S_AIs not output.
[0037]
When the load impedance of the load 2 slightly increases and the AC voltage waveform output from the current amplifying circuit 13 is distorted, the peak voltage is slightly distorted as indicated by reference numeral 45 in FIG.Gr decreases, the comparator 18 outputs the abnormal signal S indicated by reference numeral 46 in FIG._AIs output. In this case, the duty ratio determination circuit 36 outputs the abnormal signal S_AIs determined to be smaller than the reference duty ratio, and the abnormal signal S_A1Is not output.
[0038]
On the other hand, when the load impedance of the load 2 rises further, the distortion of the AC load current waveform becomes larger as indicated by reference numeral 47 in FIG. Therefore, the abnormal signal S output from the comparator 18_ABecomes large. Therefore, the duty ratio determination circuit 36 outputs the abnormal signal S indicated by reference numeral 48 in FIG._AIs determined to be larger than the reference duty ratio, and the abnormal signal S_A1Is output continuously.
[0039]
As described above, according to the power supply device 31, the output voltage waveform during the normal operationButThe comparator 18 causes the abnormal signal S_AIs output, the duty ratio determination circuit 36 outputs the abnormal signal S_AAbnormal signal S only when the duty ratio is larger than the reference duty ratio._A1Is output. As a result, during normal operation, the abnormal signal S_ACan be prevented from being output.
[0040]
Note that the present invention is not limited to the above embodiment. For example, according to the present invention, in the power supply device 31, the offset voltage output circuit 32 and the addition circuit 33 are omitted, and the analog division circuit 15 and the reference voltage output circuit 35 are replaced with the analog division circuit 15 and the reference voltage The configuration may be the same as that of the voltage output circuit 17. In this case, the load current detection voltage V_IIs the reference signal V_refA voltage corresponding to 0 A is output twice in one cycle of. Therefore, since the division by the analog division circuit 15 is performed by the value 0, an error may occur in the gain variable. In such a case, the comparator 18 outputs the abnormal signal S_AMay be output (see the abnormal signal waveform 49 in FIG. 4). However, even in this case, the duty ratio determination circuit 36 determines that the abnormal signal S is smaller than the reference duty ratio._A1By stopping the output of the above, it is possible to prevent the erroneous determination between normal and abnormal.
[0041]
In the power supply device 31 described above, the analog division circuit 15 outputs the offset voltage V_OWith the actual gain Gr (that is, the reference input signal V_refOf the load current detection voltage V_IIs divided by the reference signal V_refOf the load current detection voltage V _I Offset voltage V_OMay be configured to output a gain variable voltage corresponding to a value obtained by dividing by a value obtained by adding. That is, the gain variable voltage V in this case_G2Is represented by the following equation.
V_G2= (V_O/ Gr + V_ref) / (V_O+ V_I)
= (V_O/ Gr + V_I/ Gr) / (V_O+ V_I)
= 1 / Gr
Therefore, the gain variable voltage V_G2Is a voltage corresponding to the reciprocal of the actual gain Gr. Therefore, the reference gain variable voltage can be fixed to a voltage slightly higher than the voltage corresponding to the reciprocal of the gain G. As a result, it is not necessary to divide the reference voltage in the reference voltage output circuit 35. It can be determined at a high speed whether or not it is.
[0042]
Further, in the present embodiment, the gain variable that is the reciprocal of the actual gain Gr is compared with the reference gain variable that is the reciprocal of the gain G. However, the present invention is not limited to this, and the actual gain Gr and the gain G By comparing with the above, it is also possible to adopt a configuration in which the abnormality is determined. However, the configuration in which the gain variable, which is the reciprocal of the actual gain Gr, and the reference gain variable, which is the reciprocal of the gain G, are compared with each other when the value of the gain variable, which is the reciprocal of the actual gain Gr, decreases when the actual gain Gr decreases. Since the size is sharply increased, the comparison between the two can be performed reliably and easily, which is more preferable.
[0043]
Further, the present invention is not limited to the above embodiments, and the configuration can be appropriately changed. For example, in the present embodiment, division, addition, and the like are all performed by analog operations, but all or part of the operations may be configured by a DSP (Digital Signal Processor) capable of high-speed processing.
[0044]
【The invention's effect】
As described above, claim 1, 2According to the abnormality detection device described above, it is possible to determine whether the constant current source is open and the constant current does not flow or the current is insufficient, so that the abnormality can be reliably detected. This can prevent the destruction of the constant current source and the load by stopping the output of the constant current source, and can avoid a dangerous situation due to the output voltage of the constant current source.
[0045]
Claims1According to the described abnormality detection device, for example, when the load is released, the reciprocal of the actual gainsoSince a certain gain variable rapidly increases, the abnormality determining means can more easily determine the abnormality.
[0046]
Also,Claim2According to the abnormality detection device described above, even when the constant current source outputs an AC constant current, no error occurs in the gain variable of the division circuit, so that the abnormality determination unit can reliably determine the abnormality. it can.
[0047]
Claims3According to the abnormality detection device described above, the division by the abnormality determination unit becomes unnecessary, and thus it is possible to quickly determine whether or not an abnormality has occurred.
[0048]
Claims4According to the abnormality detection device described above, it is possible to prevent output of an abnormality signal in a normal state.
[0049]
Claims5According to the constant current power supply described, the output of the constant current of the constant current source can be stopped by the abnormal signal, so that the destruction of the constant current source and the load can be prevented, and the output voltage of the constant current source can be prevented. Can avoid dangerous situations.
[0050]
Claims6According to the above described constant current power supply device, the destruction of the constant current source and the load caused by the constant current control by the feedback control unit can be reliably prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram of a constant current power supply according to the present embodiment.
FIG. 2 is a block diagram of a constant current power supply device according to another embodiment.
FIG. 3 is a waveform diagram of a DC load current waveform and an abnormal signal in the constant current power supply device according to the present embodiment.
FIG. 4 is a waveform diagram of an AC load current waveform and an abnormal signal according to another embodiment.
FIG. 5 is a block diagram of a conventional constant current power supply device.
[Explanation of symbols]
1 constant current power supply
2 Load
11 Subtraction circuit
12 Amplification circuit
13 Current amplifier circuit
14 Resistance
15 Analog division circuit
16 Abnormality detector
17 Reference voltage output circuit
18 Comparators
31 Power supply
32 Offset voltage output circuit
33 Addition circuit
34 Abnormality detector
35 Reference voltage output circuit
36 Duty ratio judgment circuit

Claims (6)

Load current detection means for detecting a load current value of a constant current source configured to be able to supply a constant current having a value obtained by multiplying a voltage value of a reference input signal by a predetermined gain to a load, and at least the detected load current value and a gain variable detecting unit operable to detect a gain variable is approximated to the inverse of the actual gain of the constant current source based on the voltage value of the reference input signal, corresponding to the gain variable approximation to the inverse of the predetermined gain Abnormality detecting means for outputting an abnormal signal for detecting an abnormality of the constant current source or the load based on the reference gain variable and the detected gain variable , wherein the gain variable detecting means comprises: A division circuit that outputs the gain variable by dividing the voltage value of the reference input signal by a load current value, wherein the abnormality determination unit determines that the gain variable output from the division circuit corresponds to the gain variable. Abnormality detection apparatus characterized by comprising a comparator for outputting the abnormality signal when greater than the reference gain variable to respond. Load current detection means for detecting a load current value of a constant current source configured to be able to supply a constant current having a value obtained by multiplying a voltage value of a reference input signal by a predetermined gain to a load, and at least the detected load current value And a gain variable detecting means for detecting a gain variable approximated to the reciprocal of the actual gain of the constant current source based on the voltage value of the reference input signal, and approximating to a reciprocal of the predetermined gain corresponding to the gain variable. Abnormality determination means for outputting an abnormality signal for detecting abnormality of the constant current source or the load based on the reference gain variable and the detected gain variable, wherein the gain variable detection means has a predetermined constant. And a division circuit that divides at least the voltage value of the reference input signal by the added current value to output the gain variable. The abnormality determining means divides at least a voltage value of the reference input signal by an addition current value obtained by adding the predetermined constant to the load current value at the predetermined gain, wherein the gain variable output from the division circuit is provided. abnormal detector you and outputting the abnormality signal when greater than obtained and the reference gain variable corresponding to the gain variable by. The division circuit is configured to add a value obtained by adding the voltage value of the reference input signal to a division value obtained by dividing the predetermined constant by the actual gain obtained by dividing the voltage value of the reference input signal by the load current value. the output as a gain variable by dividing sum current value, the abnormality determination means according to claim 2, wherein the gain variable outputs the abnormality signal when greater than before Kimoto quasi gain variable Abnormality detection device as described. The apparatus further includes a duty ratio determination unit that inputs the abnormal signal and outputs a new abnormal signal when a duty ratio of the abnormal signal with respect to one cycle of the reference input signal is greater than a predetermined duty ratio. The abnormality detection device according to any one of claims 1 to 3 . An abnormality detection device according to any one of claims 1 to 4 , and the constant current source configured to stop output of the constant current by the abnormality signal output from the abnormality detection device. A constant current power supply device characterized by the above-mentioned. 6. The constant current power supply according to claim 5, further comprising feedback control means for controlling the load current value to be constant based on a detected voltage corresponding to the detected load current value and the reference input signal. apparatus.

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