JPS5856007A - Power source device - Google Patents

Abstract

PURPOSE:To suppress the generation of heat and to control a load current precisely by providing a switching type voltage control circuit which varies a voltage optionally in front of a constant current circuit and a load. CONSTITUTION:A voltage control circuit 12 holds a voltage V2 between points (e) and (g) a little bit higher than a load voltage V1 between points (f) and (g) to put a transistor (TR)13 and a current detecting resistance 14 in normal operation. In the circuit 12, the time when the unsaturated area of a TR15 for switching is used is extremely short, so the generation of heat is less. The generation of heat in a circuit 10 is less because the voltage V2 is controlled to a little bit above the V1. Further, the circuit 10 outputs a load currentI1 which is precisely proportional to an optional voltage outputted from a load current setting circuit 11.

Description

[Detailed description of the invention] The present invention relates to a power supply device that can arbitrarily vary load current.

In general, power supplies that can arbitrarily vary load current are widely used in various types of control circuits, such as torque control circuits for electromagnetic brakes and temperature control circuits for heaters. As an example of a circuit of a conventional power supply device, as shown in Fig. 1, there is a load current setting circuit 1 that outputs the load current setting value as a voltage signal, and a voltage signal output from the load current setting circuit 1 that uses a series regulator to convert the load current. There is a circuit consisting of a constant current circuit 2 that maintains a value proportional to Since the load voltage v1 between a and c is changed, the voltage W-L x (vo-vl) is released as heat from the transistor 4 and current detection resistor 5 of the constant current circuit 2, and the power is This impairs utilization efficiency and increases the size and weight of heat dissipation devices such as heat dissipation fins.

In order to eliminate these drawbacks due to heat generation, the second
Using a chopper-type voltage control circuit 6 as shown in the figure, the voltage is controlled to keep the load current IL at an arbitrary value by switching the transistor 8 via the comparator 7 according to the load current I. A method of suppressing heat generation by configuring a constant current circuit is considered, but in this case, it is difficult to provide a load current setting circuit 9 due to the switching characteristics of the transistor 8 and the response time of the comparator 7.

The present invention aims to eliminate these drawbacks, suppress heat generation, and control load current with high precision.The basic configuration for achieving the above objectives is a power supply device having a constant current circuit that can arbitrarily vary the load current. , a switching type voltage control circuit that can arbitrarily vary the voltage is provided in front of the constant current circuit and the load, and the output voltage of the constant voltage circuit is changed in accordance with changes in the current of the load. It is something that does.

An embodiment of the present invention will be described below with reference to FIG. Third
10 in the figure is a series regulator one-type constant current circuit similar to that in Figure 1, 11 is a load current setting circuit, and 12
is a chopper that controls the voltage between e and g to be slightly higher than the load voltage v1 between r and g and the minimum voltage △V required for Ω to normally operate the transistor 13 and current detection resistor 14. 16 is a load.

Here, since the time for using the non-saturated region of the voltage 15 due to switching such as a chopper method is extremely short, much less heat is generated compared to a series regulator type that always uses the non-saturated region of the transistor. Also, the heat generated in the series regulator type constant current circuit 10 is
Voltage between e and g V2 y'fi is normally controlled to be slightly higher than K, v1+△V, so W = (V2 'V+) XIL ≠△vx
x.

Even when combined with the amount of heat generated by the chopper type voltage control circuit 12, the amount of heat generated is far less than that of the circuit shown in FIG.

Further, the series regulator type constant current circuit 1o can output a load current IL that is accurately proportional to the voltage output from the load current setting circuit 11. Therefore, by using the above power supply device, the load current can be arbitrarily controlled with high precision with a small amount of heat generation, and it can be said that the power supply device is extremely useful as a power supply device that can arbitrarily and accurately vary the load current.

[Brief explanation of drawings]

1 and 2 are circuit diagrams of a conventional example of a power supply device that can arbitrarily vary the load current, and FIG. 3 is a circuit diagram of an embodiment of the power supply device of the present invention. 1o: Constant current circuit, 11: Load current setting circuit, 12: Voltage control circuit. Name of agent: Patent attorney Toshio Nakao and one other person iA
Figure 1

Claims (1)

[Claims] It has a constant current circuit that can arbitrarily vary the load current, and a switching type voltage control circuit that can arbitrarily vary the voltage is provided in front of the constant current circuit and the load, and the voltage control circuit that can arbitrarily vary the voltage according to the change in the current of the load is provided. A power supply device characterized by changing the output voltage of a constant voltage circuit.